221265661 has 8 divisors (see below), whose sum is σ = 228076760. Its totient is φ = 214498368.

The previous prime is 221265637. The next prime is 221265673. The reversal of 221265661 is 166562122.

It can be written as a sum of positive squares in 4 ways, for example, as 38204761 + 183060900 = 6181^2 + 13530^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 221265661 - 2¹¹ = 221263613 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221265601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 546 + ... + 21043.

It is an arithmetic number, because the mean of its divisors is an integer number (28509595).

Almost surely, 2^221265661 is an apocalyptic number.

It is an amenable number.

221265661 is a deficient number, since it is larger than the sum of its proper divisors (6811099).

221265661 is a wasteful number, since it uses less digits than its factorization.

221265661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21903.

The product of its digits is 8640, while the sum is 31.

The square root of 221265661 is about 14875.0012100840. The cubic root of 221265661 is about 604.8365207273.

The spelling of 221265661 in words is "two hundred twenty-one million, two hundred sixty-five thousand, six hundred sixty-one".